The House and Senate approved Solar Energy Systems Tax credits that are available for qualified solar water heating and photovoltaic systems. The credits are available for systems "placed in service" from January 1, 2006 through December 31, 2016. The tax credit is for 30% of the cost of the system. This credit is not limited to the $500 home improvement cap. Call your Tax Preparer for information in your particular case.
You can use www.dsireusa.org to locate other financial incentives and rebate programs for renewable energy systems installed in the United States.